Rotary bearing, also known as slewing bearing, is a large bearing which can bear large axial load, radial load and overturning moment at the same time.Turntable bearings are generally equipped with mounting hole, inner gear or outer gear, lubricating oil hole and sealing device, thus can make the main structure design compact, reliable, easy to maintain.
Four point contact ball bearings, double row Angle contact ball bearings, cross cylindrical roller bearings, cross tapered roller bearings and three row cylindrical roller bearings, with or without teeth, outer teeth and inner teeth.The four-point contact ball bearing has a high static load capacity.The cross cylindrical roller bearing has high dynamic load capacity.The cross tapered roller bearing has higher bearing rigidity and higher turning precision through preinterference.
Rotary disc bearings are widely used in lifting machinery, mining machinery, construction machinery, port machinery, ship machinery and high-precision radar machinery and missile launcher and other large rotary devices.
The application of turntable bearing in various fields
Yaw bearings are mounted at the connection between the tower and the cockpit, and the variable-pitch bearings are mounted at the connection between the root of each blade and the hub.One set of yaw bearings and three sets of variable propeller bearings are used for each wind turbine.The materials of yaw and variable rotor bearing rings are 42CrMo. The heat treatment is based on the integral tempering treatment and the raceway surface quenching.Yaw, variable propeller bearing force is complex, and the impact and vibration of the larger, therefore, the bearing is required to be able to bear both impact, and can bear a larger load.The main engine life of the wind turbine requires 20 years, the cost of bearing installation is large, so the life of yaw, rotor bearing should also reach 20 years.The matrix hardness of the bearing ring is 240-280hb, which can withstand impact without plastic deformation. Meanwhile, the surface hardening hardness of the raceway reaches 55-62hrc, which can increase the contact fatigue life and guarantee the long service life of the bearing.
2. Marine crane
Marine cranes generally use double displacement ball, four point contact ball, three row roller internal tooth structure of the rotary disc bearings, according to the bearing capacity of different, three row roller rotary disc bearings are usually used for heavy cranes, four point contact ball rotary disc and double displacement diameter ball rotary disc bearings for light cranes.
Because the crane works in the environment of -20°C - +45°C, this kind of bearing requires high mechanical properties of the material.
3. Offshore platform crane
According to the bearing capacity requirements, the offshore platform crane usually USES four-point contact ball turntable and three rows of roller inner gear turntable bearings.
The turntable bearing applied to offshore platform crane has special material requirements. The mechanical properties of the material should ensure the safety coefficient under the limit load. The charpy impact test of forging sample can reach the average value of 42j@-20 °C or 27j@-40 °C.The finished bearing shall be certified by the classification society.
Port mobile crane
Port cranes usually use three row roller wheel bearings of 4 m diameter with inner or outer teeth to withstand high overturning moments.
5. Stacker and reclaimer
The rotary table bearings used in stacker and retractor are usually combined ball and column type, three row roller type and cross roller type, most of which are over 3 meters in diameter.Due to the harsh working environment and large dust, this kind of bearing has the characteristics of high bearing capacity, long service life and good sealing performance.
6. The ferris wheel
Used for four-point contact ball turntable bearing on ferris wheel, the outer diameter is 4100mm and the thickness is 85mm
7. Ship unloader
The rotary disc bearing used in ship unloading machine usually adopts the structure of three rows of rollers with outer teeth, with a diameter of about 4 meters.
Tower crane of 8.
Tower machine bearings usually use small size four - point contact ball wheel bearings or double volleyball wheel, diameter is not more than 2 meters.
9. Radar antenna
Short-wave antenna generally USES three row roller structure of the turntable bearings, rotation speed is slow.
Shield tunneling machine with rotary table bearings from 2.5 meters to 6 meters in diameter, some larger diameter, this kind of bearings in very harsh conditions, bearing load, corrosion resistance, short life.
11. Ladle turntable
Ladle turntable bearings usually use three row roller structure, because of the dust and high temperature conditions under the bad conditions, maintenance, grease and sealing strip have high requirements.
12. Construction machinery
Construction machinery bearings usually use small size four-point contact ball bearings, diameter is not more than 2 meters.